/**

 * Relational pipes

 * Copyright © 2019 František Kučera (Frantovo.cz, GlobalCode.info)

 *

 * This program is free software: you can redistribute it and/or modify

 * it under the terms of the GNU General Public License as published by

 * the Free Software Foundation, either version 3 of the License, or

 * (at your option) any later version.

 *

 * This program is distributed in the hope that it will be useful,

 * but WITHOUT ANY WARRANTY; without even the implied warranty of

 * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the

 * GNU General Public License for more details.

 *

 * You should have received a copy of the GNU General Public License

 * along with this program. If not, see <http://www.gnu.org/licenses/>.

 */

#pragma once

#include <iostream>

#include <string>

#include <sstream>

#include <vector>

#include <relpipe/writer/typedefs.h>

namespace relpipe {

namespace in {

namespace recfile {

using namespace relpipe::writer;

class RecfileCommand {

private:

	enum class RecfileLineType {

		METADATA,

		DATA,

		SEPARATOR,

		COMMENT,

		END,

	};

	class RecfileHandler {

	private:

		RelationalWriter* writer;

		void metadata(const string_t& name, const string_t& value) {

			std::wcerr << L"metadata(" << name << L", " << value << L");" << std::endl; // TODO: remove debug

		}

		void data(const string_t& name, const string_t& value) {

			std::wcerr << L"data(" << name << L", " << value << L");" << std::endl; // TODO: remove debug

		}

		void comment(const string_t& value) {

		}

		void separator() {

			std::wcerr << L"separator()" << std::endl; // TODO: remove debug

		}

		void end() {

		}

	public:

		RecfileHandler(RelationalWriter* writer) : writer(writer) {

		}

		virtual ~RecfileHandler() {

		}

		void logicalLine(RecfileLineType type, const string_t& name = L"", const string_t& value = L"") {

			switch (type) {

				case RecfileLineType::METADATA: return metadata(name, value);

				case RecfileLineType::DATA: return data(name, value);

				case RecfileLineType::COMMENT: return comment(value);

				case RecfileLineType::SEPARATOR: return separator();

				case RecfileLineType::END: return end();

			}

		}

	};

	enum class ParserState {

		START,

		NAME,

		VALUE,

		VALUE_CONTINUATION,

		COMMENT,

		END,

	};

	class RecfileParser {

	private:

		wstring_convert<codecvt_utf8<wchar_t>> convertor; // TODO: support also other encodings or are recfiles always in UTF-8?

		RecfileHandler& handler;

		void emitLogicalLine(RecfileLineType& type, std::stringstream& name, std::stringstream& value) {

			handler.logicalLine(type, convertor.from_bytes(name.str()), convertor.from_bytes(value.str()));

			name.str("");

			name.clear();

			value.str("");

			value.clear();

			type = RecfileLineType::DATA;

		}

	public:

		RecfileParser(RecfileHandler& handler) : handler(handler) {

		}

		virtual ~RecfileParser() {

		}

		void parse(std::istream& input) {

			ParserState state = ParserState::START;

			RecfileLineType type = RecfileLineType::DATA;

			std::stringstream name;

			std::stringstream value;

			char ch;

			while (state != ParserState::END && input.good()) {

				ch = input.get();

				if (input.eof()) continue;

				switch (state) {

					case ParserState::START:

						if (ch == '%') {

							type = RecfileLineType::METADATA;

							break;

						} else if (ch == ' ') {

							break;

						} else if (ch == '\n') {

							handler.logicalLine(RecfileLineType::SEPARATOR);

							break;

						} else if (ch == '#') {

							type = RecfileLineType::COMMENT;

							state = ParserState::COMMENT;

							if (input.get() != ' ') input.unget();

							break;

						} // else → name

					case ParserState::NAME:

						if (ch == ':') {

							state = ParserState::VALUE;

							if (input.get() != ' ') input.unget();

						} else {

							name << ch;

						}

						break;

					case ParserState::VALUE:

						if (ch == '\n') state = ParserState::VALUE_CONTINUATION;

						else value << ch;

						break;

					case ParserState::VALUE_CONTINUATION:

						if (ch == '+') {

							state = ParserState::VALUE;

							if (value.tellp()) value << '\n';

							if (input.get() != ' ') input.unget();

						} else {

							input.unget();

							state = ParserState::START;

							emitLogicalLine(type, name, value);

						}

						break;

					case ParserState::COMMENT:

						if (ch == '\n') {

							state = ParserState::START;

							emitLogicalLine(type, name, value);

						} else {

							value << ch;

						}

						break;

					default:

						throw RelpipeWriterException(L"Unknown ParserState: " + std::to_wstring((int) state) + L" in RecfileParser."); // TODO: better exception

				}

			}

			emitLogicalLine(type, name, value);

			handler.logicalLine(RecfileLineType::END);

		}

	};

public:

	void process(std::istream& input, std::ostream& output) {

		unique_ptr<RelationalWriter> writer(Factory::create(output));

		RecfileHandler handler(writer.get());

		RecfileParser parser(handler);

		parser.parse(input);

	}

};

}

}

}